/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.facebook.thrift.transport;

import com.facebook.thrift.utils.Logger;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * This is the most commonly used base transport. It takes an InputStream and an OutputStream and
 * uses those to perform all transport operations. This allows for compatibility with all the nice
 * constructs Java already has to provide a variety of types of streams.
 */
public class TIOStreamTransport extends TTransport {

  private static final Logger LOGGER = Logger.getLogger(TIOStreamTransport.class.getName());

  /** Underlying inputStream */
  protected InputStream inputStream_ = null;

  /** Underlying outputStream */
  protected OutputStream outputStream_ = null;

  /**
   * Subclasses can invoke the default constructor and then assign the input streams in the open
   * method.
   */
  protected TIOStreamTransport() {}

  /**
   * Input stream constructor.
   *
   * @param is Input stream to read from
   */
  public TIOStreamTransport(InputStream is) {
    inputStream_ = is;
  }

  /**
   * Output stream constructor.
   *
   * @param os Output stream to read from
   */
  public TIOStreamTransport(OutputStream os) {
    outputStream_ = os;
  }

  /**
   * Two-way stream constructor.
   *
   * @param is Input stream to read from
   * @param os Output stream to read from
   */
  public TIOStreamTransport(InputStream is, OutputStream os) {
    inputStream_ = is;
    outputStream_ = os;
  }

  /**
   * The streams must already be open at construction time, so this should always return true.
   *
   * @return true
   */
  public boolean isOpen() {
    return true;
  }

  /** The streams must already be open. This method does nothing. */
  public void open() throws TTransportException {}

  /** Closes both the input and output streams. */
  public void close() {
    if (inputStream_ != null) {
      try {
        inputStream_.close();
      } catch (IOException iox) {
        LOGGER.warn("Error closing input stream.", iox);
      }
      inputStream_ = null;
    }
    if (outputStream_ != null) {
      try {
        outputStream_.close();
      } catch (IOException iox) {
        LOGGER.warn("Error closing output stream.", iox);
      }
      outputStream_ = null;
    }
  }

  /** Reads from the underlying input stream if not null. */
  public int read(byte[] buf, int off, int len) throws TTransportException {
    if (inputStream_ == null) {
      throw new TTransportException(
          TTransportException.NOT_OPEN, "Cannot read from null inputStream");
    }
    int bytesRead;
    try {
      bytesRead = inputStream_.read(buf, off, len);
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
    if (bytesRead < 0) {
      throw new TTransportException(TTransportException.END_OF_FILE);
    }
    return bytesRead;
  }

  /** Writes to the underlying output stream if not null. */
  public void write(byte[] buf, int off, int len) throws TTransportException {
    if (outputStream_ == null) {
      throw new TTransportException(
          TTransportException.NOT_OPEN, "Cannot write to null outputStream");
    }
    try {
      outputStream_.write(buf, off, len);
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }

  /** Flushes the underlying output stream if not null. */
  public void flush() throws TTransportException {
    if (outputStream_ == null) {
      throw new TTransportException(TTransportException.NOT_OPEN, "Cannot flush null outputStream");
    }
    try {
      outputStream_.flush();
    } catch (IOException iox) {
      throw new TTransportException(TTransportException.UNKNOWN, iox);
    }
  }
}
